2-47. The bacterium Streptococcus pneumoniae has a virulent S strain and a nonvi

Question

2-47. The bacterium Streptococcus pneumoniae has a virulent S strain and a nonvirulent R strain. The S strain is lethal to mice. The S strain contains a chemical factor that can transform the R strain to be virulent. The diagram shows a series of experiments conducted by injecting combinations of these strains into mice to identify the transforming factor If DNA is the transforming factor, match the expected results of each experiment as "mice alive" or "mice dead" R strain (nonvirulent) S strain (virulent) Alive Dead R strain and heat-treated S strain R strain and heat-treated S strain with po?ysaccharides, ipids, RNA, and R strain and heat-treated S strain with oids, RNA, proteins, DNA destroyed Choose "A" for "mice alive". Choose "B" for "mice dead". 42. Result of Experiment A is 43. Result of Experiment B is 44. Result of Experiment C is 46. Result of Experiment E is 47. Result of Experiment F is 48. Which enzyme is responsible for the replication of chromosome ends in germ cells and certain proliferating somatic cells? a, DNA polymerase ? c. DNA ligase d. Telomerase e. Geminin 49. The diagram depicts DNA that is undergoing replication. Which is the leading strand? HAHH a. strand A b. strand B 50. The Meselson and Stahl experiment starts with E. coli containing 15N/15N labeled DNA grown in 14N media. Which result did Meselson and Stahl observe by sedimentation equilibrium centrifugation to provide strong evidence for the a. The first generation has hybrid 15N/14N DNA, and the second generation has hybrid 15N/14N DNA. No b. Both the first and second generation have both 15N/15N DNA and 14N/14N DNA. No hybrid 15N/14N DNA wa c. The first generation has hybrid 15N/14N DNA, and the second generation has both hybrid 15N/14N DNA a semiconservative model of DNA replication? 15N/15N DNA or 14N/14N DNA was observed 14N/14N DNA. No 15N/15N DNA was observed 51-54. Match each protein to its role in DNA replication using the following choices: a DNA topoisomerase b. Helicase

Explanation / Answer

42. Mice alive, A

43. Mice dead, B

44. Mice alive, A

45. Mice dead, B

46. Mice dead, B

47. Mice alive, A

DNA is the transforming principle which can be transformed from heat-killed S strain to R strain which turns R strain to be virulent. The cause of infection is DNA. Destroying DNA will also inactivate the virulence factor. In case of heat killed S strain, DNA survives but cell containing it dies and hence can not cause infection.

48. d. Telomerase

49. a. Strand A. Leading strand is continuous (there are no Okazaki fragments).

50. c

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.